Information Technology Reference
In-Depth Information
is introduced into the diagram to merge flows that are split by the
decision node. At the end of the algorithm, a set of activity diagrams
representing all the feasible composite services is obtained.
6.3.2 Service Composition Planner Supporting
Branch Structures
Service composition planner (SCP) is the main algorithm that can
introduce branch and choice structures into the composite service. It
has three subprocedures, that is, processing preference with conditional
expression (PPCE), processing preference with multiple cases (PPMC),
and processing preference with priority (PPP). These subprocedures
deal with the following user/domain preferences, respectively:
1. Service preference with
condition
WS
2
;
2. Service preference with
switch(condition){case C
1
?
WS
1
:
:
WS
1
;
case
C
2
:
WS
2
;
...;
case C
n
:
WS
n
;
}
; and
...
3. Priority:
WS
1
WS
2
WS
n
.
¼
(I
A
,O
E
; Pref, QoS)
represents the user's request where
I
A
and
O
E
are the
input and output parameters.
Pref
represents a set of personalized
preferences defined by the service requester or common preferences
in a specific domain; while QoS represents a set of standards of the
service's quality parameters defined by the service requester.
It outputs a set of activity diagrams, each of which represents a
feasible composite service.
n
j
,
j
In the following algorithm,
C
is a set of available services.
Req
0, 1, 2, . . . represents an action node.
S
j
represents its state information. In the following algorithms, set NS is
used to record all the action nodes to be processed later. Note that the
subprocedures maintain the connection with the main algorithm SCP
through this set.
¼
Algorithm SCP. (C; Req): Service Composition Planner
Input:
C¼
(WS
1
;
WS
2
;
...
;
WS
n
)
, service community, a set of available
services; and
Req
¼
(I
A
,
O
E
;
Pref
,
QoS)
, the user's request.
